I'm considering unlocking the bootloader on my Verizon Galaxy S3 (SCH-I535). However, a guide I was reading made this statement:

Once you have unlocked your phone’s bootloader using this app, you must not receive any over-the-air (OTA) updates or via Samsung Kies. Doing so will result in bricking your phone.

I understand that bricking a phone means rendering it unusable, but does this also mean unrecoverable? When a phone is "bricked", does that mean it is virtually impossible to restore it to a working state?

2 Answers
2

The term "brick" usually refers to the stone, which means: "device can only be used as paper-weight". Taken literally, there's no way to "unbrick".

However, you also find terms like "hard-brick" and "soft-brick" used, which makes the term "brick" less absolute: A soft-brick is something you easily can recover from (count it as a "temporary paper-weight"), mostly by software-based solutions (e.g. re-flash your phone) -- while a "hard-brick" is rather meant in the way the original term points to.

Still, technically spoken, even a "hard-bricked" device could be "unbricked" -- but mostly this is more expensive then getting a new device.

As for the warranty declaration you quoted: For a normal user, it's almost impossible to (hard-) brick his device. Even when flashing a custom ROM, this can rarely happen, as there are many security-layers involved. Almost always you can boot your device into some fall-back mode where it is at least recognized by some "flashing software", so you could simply flash another/the original firmware back. Which means, the risk you are taking is to "soft-brick" your device1. A "hard-brick" is quite unlikely with "normal operations" like rooting or flashing custom ROMs.

My xperia c is not giving any response on pressing any combinations of keys. I installed Z2 rom in it. After successful installation, it hasn't reboot. It is showing a response only when connected to charger or PC via usb cable and that is the display of a RED LIGHT and nothing else. Does it means it is hard bricked? Suggest me what to do..
–
choxxApr 22 at 19:02

Brick is a much-hyped word that gets bandied about with-out understanding what it is.

There's two types of brick, hard and soft. Lets go through this to make the distinction clearer.

Hard this is where the handset will absolutely refuse to boot at the press of the power button. Diagnostics: Dead screen, no power. That is the symptom of a hard brick. Reason: This can happen by inadvertently pulling the cable when flashing a ROM or even an update via the handset's supporting software such as Samsung Kies, Sony's PC Companion Suite etc. That is the worst case, that is why in this scenario, always, make, sure that no cable gets pulled unless told so by the supporting software in question. The other way is this, flashing in that manner when the battery power is low. Hence for that reason, it is recommended to have at least 75% of battery power in place prior to doing the update in that fashion. Its known as hard-brick, and requires specialist cables and stripping the device down to the circuitary board to revive it via JTAG cables.

Soft - this can happen through a bad flashing of the ROM in which yields the following. Diagnostics: it has power when the power button is pressed, and/or, the screen comes on. Reason: It can be a user error on this part. For example, failing to clear/wipe the data/cache, can cause Android to go into a boot-loop because of the mis-matches with the Android's virtual machine and the apps installed, or more than likely, a corrupted dalvik cache. The other, is flashing a ROM that is not designated for the handset which can cause the kernel to go into a boot-loop. This is generally easier to fix, but hangs, that is known as a soft-brick.

With those two separate forms of brick, it is generally speaking, a scare-mongering tactic.

The one pure simple reason why carriers do not recommend unlocking the boot-loader, is not just for the warranty.

Its more down to the fact, if the handset ever gets stolen, then unlocking the boot-loader will wipe everything, and re-initialize the handset to factory state, thereby all your contacts, call logs, messages and apps gets wiped cleanly. Also, this is to reduce the amount of support in the carriers, with people calling in or ringing up the technical support, "What happened with my handset - I did something and lost my contacts?"

Just to finish off this answer, you can revert it back, by re-locking the boot-loader at a later stage if you wish, that is in the event the hardware got damaged and hand it back in for repairs.

Great information, and I'm glad to hear that I can relock my bootloader if need be.
–
EricSep 21 '12 at 21:18

That said, you also can un-root (even easier as relock I'd say). But I doubt you'll ever feel like it -- unless in a case of warranty, of course :)
–
IzzySep 21 '12 at 21:37

My xperia c is not giving any response on pressing any combinations of keys. I installed Z2 rom in it. After successful installation, it hasn't reboot. It is showing a response only when connected to charger or PC via usb cable and that is the display of a RED LIGHT and nothing else. Does it means it is hard bricked?
–
choxxApr 22 at 19:01

@choxx oh dear, you flashed a Z2 rom ( for Sony Xperia Z2 ) on a Xperia C, that rom is not compatible right? You have checked and confirmed this? In any case, sounds like a soft brick, try reverting back, but this time, USE a specific rom designated for Xperia C in your case.
–
t0mm13bJun 5 at 23:23